Scalable Formation of Concentrated Monodisperse Lignin Nanoparticles by Recirculation-Enhanced Flash Nanoprecipitation

A highly controllable and scalable process for fabrication of large amounts of concentrated lignin nanoparticles (LNPs) is reported. These lignin core nanoparticles are formed through flash nanoprecipitation, however, scaling up of the fabrication process requires fundamental understanding of their operational formation mechanism and surface properties. It is shown how a semicontinuous synthesis system with a recirculation loop makes it possible to produce flash precipitated lignin nanoparticles in large amounts for practical applications. The roles of the process parameters, including flow rates and lignin concentration, are investigated and analyzed. The results indicate that the LNPs are formed by a process of continuous burst nucleation at the point of mixing without diffusive growth, which yields nanoparticles of highly uniform size following a modified LaMer nucleation and growth mechanism. This mechanism makes possible facile process control and scale-up. Effective control of the resulting nanoparticle size is achieved through the initial concentration of lignin in the injected solution. The impressive capability to produce suspensions of any predesigned multimodal distribution is demonstrated. The resulting nanofabrication technique can produce large volumes of concentrated LNP suspensions of high stability and tightly controlled size distributions for biological or agricultural applications.     

Assembling carbon nanotubosomes using an emulsion-inversion technique

Novel micro-capsules (carbon nanotubosomes) have been fabricated by cross-linking shells of amine-functionalized multi-walled carbon nanotubes (MWNTs) produced by their adsorption on water-in-oil emulsion drops followed by an emulsion-inversion.     

On the density of the set of generators of a polynomial algebra

Let be the polynomial algebra over a field of characteristic . We call a polynomial coordinate (or a generator) if for some polynomials . In this note, we give a simple proof of the following interesting fact: for any polynomial of the form where is a polynomial without constant and linear terms, and for any integer , there is a coordinate polynomial such that the polynomial has no monomials of degree . A similar result is valid for coordinate -tuples of polynomials, for any . This contrasts sharply with the situation in other algebraic systems.

On the other hand, we establish (in the two-variable case) a result related to a different kind of density. Namely, we show that given a non-coordinate two-variable polynomial, any sufficiently small perturbation of its non-zero coefficients gives another non-coordinate polynomial.

     

Detection of Trace Zinc by an Electrochemical Microsensor based on Carbon Nanotube Threads

Carbon nanotubes (CNTs) have attracted intense interest due to their excellent properties, such as increased electrode surface area, fast electron transfer rate, significant mechanical strength and good chemical stability. CNT threads, spun from shorter CNTs, inherit the advantages of CNTs, while avoiding the potential toxicity caused by individual CNTs. In this work, microelectrodes based on CNT threads were used to detect trace zinc by anodic stripping voltammetry with an estimated detection limit of 1.4 nM without mercury or bismuth films. CNT threads showed promise for measuring trace metals in small sample volumes without stirring such as encountered in some in vivo and in vitro applications.     

Note on the distribution of poles of the scattering matrix

Trapping obstacles, having at least one isolated multiple reflecting trapping ray, are considered. It is proved that for every ε > 0 there are poles λ_j of the scattering matrix such that $\text{0 <}\text{Im}\text{λ}{}_{\mathrm{j}}\text{< ε}\text{Log}\text{|λ}{}_{\mathrm{j}}\text{¦}$.     

Nucleation in electrochemical growth of the Ag(100) crystal face: determining the nucleus size via the nucleation theorem

We employ the nucleation theorem for a model-independent determination of the size of the two-dimensional (2D) Ag nucleus with the aid of experimental data for the nucleation-mediated electrochemical growth of the Ag(100) crystal face in aqueous solution of AgNO(3) at 318 K. These data are for the stationary rate of 2D nucleation, for the initial portion of the potentiostatic current transient pertaining to atomically smooth face, and for the galvanostatic current corresponding to stationary growth of the face. It turns out that the 2D nucleus is constituted of 17-64 Ag atoms when the overpotential is in the range of 12-22.4 mV. Upon expressing the overpotential in terms of supersaturation, it is found that the experimental data for the size of the 2D Ag nucleus are in conformity with existing simulation data for the size of the 2D nucleus on the (100) face of Kossel crystal (the simulation nucleus contains 1-30 atoms). It is found as well that the Gibbs-Thomson equation of the classical theory of 2D nucleation describes very well the supersaturation dependence of the size of both the Ag and the simulation nucleus.     

Structural engineering of pMHC reagents for T cell vaccines and diagnostics

MHC class I peptide complexes (pMHC) are routinely used to enumerate T cell populations and are currently being evaluated as vaccines to tumors and specific pathogens. Herein, we describe the structures of three generations of single-chain pMHC progressively designed for the optimal presentation of covalently associated epitopes. Our ultimate design employs a versatile disulfide trap between an invariant MHC residue and a short C-terminal peptide extension. This general strategy is nondisruptive of native pMHC conformation and T cell receptor engagement. Indeed, cell-surface-expressed MHC complexes with disulfide-trapped epitopes are refractory to peptide exchange, suggesting they will make safe and effective vaccines. Furthermore, we find that disulfide-trap stabilized, recombinant pMHC reagents reliably detect polyclonal CD8 T cell populations as proficiently as conventional reagents and are thus well suited to monitor or modulate immune responses during pathogenesis.     

A novel gel deformation technique for fabrication of ellipsoidal and discoidal polymeric microparticles

A simple fabrication technique for anisotropic particles of ellipsoidal/discoidal shape has been developed, based on stretching/compressing of oil-in-water emulsion templates embedded into an elastic aqueous gel; a range of solid anisotropic microparticles have been fabricated by polymerising of the deformed oil drops in the elastic gel matrix and their shape and aspect ratios have been studied as a function of the gel deformation.